Making a Fiberglass Mast Sleeve

First time I broke my mast sleeve, it was just a simple tube from 3/4" lumber, with screws from the bottom of the hull coming up thru into the sleeve. While out sailing at Lake Pleasant during Gordon's Peachland Endurance Race, I was bobbing and baking all day - and the sleeve broke free. At the time I thought it was just the fact that the screws were holding into 3/4" wood, and that wasn't strong enough.

broken mast sleeve

I repaired my mast sleeve by adding a triangle piece to the bottom, and then thru-bolting that triangle to the bottom plus a couple of bolts on the sides. Figured it would be as strong as ever, but it broke again! This time the front of the sleeve broke taking some of the deck with it.

After looking at the damage, I got the feeling that it wasn't because of the strength of the sleeve, but rather that I had a 3/16" gap around my mast, and that was just enough that as I bobbed around in the power boat wakes, it would thunk the mast back and forth in the sleeve, which was doing the damage. That plus I am using a 16' tall mast, and the sleeve is only 16" tall.

I thought about just repairing the sleeve I had, then shaping the mast to make it fit tighter, but also saw this opportunity to make a fiberglass mast sleeve, sort of a test for later when I build my all fiberglass PD. For the mold, I started off with a fun noodle, stuffed a stick down the middle to make it straight. Then measured the angle from the sleeve to the bottom, and cut the noodle to the same angle.

I used marine goop to glue the noodle to a piece of cardboard. Leaning against the wall to keep that angle while the glue cured. Then I wrapped it all in masking tape so the epoxy wouldn't stick to it. (the epoxy did stick to the tape)

I glassed the sleeve mold and also made a partner. The mold for the partner is the same as the sleeve, but I wrapped red vynil tape around the fun noodle to increase it's diameter.

I setup my new parts and discovered that I screwed up the angle between the bottom and the sleeve. I measured the gap at the front of the sleeve, and made a wedge with an air pocket the same height as the gap.

Filled it up with some epoxy....

Presto, problem solved.

I repaired my damaged deck and added a perimeter where the new glass parts will be bolted on.

Final test fit before shaving the partner and bolting everything on. I used a stick to push the foam out. It didn't come out in one piece, I pushed small pieces out while poking at it. The masking tape is still stuck to the inside of the sleeve, but figure over time it will wear off, or just stay there.

I also cut the top of the sleeve off so it is flush with the partner.

I put 4 bolts in the partner, and 4 bolts thru the bottom of the sleeve flange into the bottom.

Back to the original problem - the gap between the mast and the sleeve. To keep the mast from thunking around in the sleeve, I wrapped fiberglass around the base of the mast to match the sleeve diameter. It took a bit of sanding and fitting, but now it works really well.

The mast rotates in the sleeve, so to help it do so, I cut a wedge and dropped it to the bottom of the sleeve to make a flat bottom to the tube. Also I dropped a plastic disk in there too (made from milk jug), now the mast sits flat on the disk and rotates easily.